Cruise control systems for vehicles have been widely used for convenient travel. Adaptive cruise control systems (ACCSs) improve some features over standard systems, such as adjusting the speed of the vehicle in response to changing traffic conditions. For example, a vehicle under the operation of an ACCS can monitor surrounding areas using range-finding techniques. Should the vehicle encounter a slow-moving vehicle in its lane, the ACCS can reduce the speed of the vehicle to prevent a collision, while continuing to operate the vehicle. Traditional cruise control systems would require the operator to disengage the cruise control system and resume manual operation of the vehicle.
Under certain driving conditions, an ACCS can bring the vehicle to a complete stop. When a complete stop occurs, it can be difficult for the ACCS to determine the circumstances of the stop. A complete stop could result from congested traffic, after which resumption of speed at a safe following distance would be an appropriate action for the system to undertake. A complete stop could also occur behind another vehicle at a stop sign. When the preceding vehicle advances through the intersection, the way would be clear for the vehicle to resume its cruising speed, which would be an undesirable result. Accordingly, a conventional ACCS is unable to operate the vehicle properly from a stop.
Additionally, an ACCS typically interacts with an electronic engine controller. Owing to the multiply-connected nature of the ACCS, with couplings to a variety of sensors and inputs, it is possible that the ACCS will reach a state wherein it has an incorrect record of the current operational state of the vehicle. For example, the ACCS could have received an incorrect signal indicating the vehicle is stopped from an improperly-functioning sensor, when in fact the vehicle is still moving. Thus, a conventional ACCS could transmit an inappropriate command signal following an incorrect sensor reading.